Thread-cutting tool



E. P. DAVIS.

THREAD CUTTING TOOL.

APPLICATION FILED-MAR. 25. 1918.

- Patented Mar. 2, 1920.

UNITED STATES PATENT OFFICE.

EDWIN P. DAVIS, 0F BRIDGEPORT, CONNECTICUT.

THREAD-CUTTING TOOL.

Application filed March 25, 1918.

To all whom it may concern:

Be it known that'I, EDWIN P. DAVIS, a citizen of the United States,residing at Bridgeport, in the county of Fairfield and State ofConnecticut, have invented certain new and useful Improvements inThread- Cutting Tools; and I do hereby declare the followlng to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

My invention relates to cutting-tools to be operated by lathes andespecially tools for forming threads.

It is practically impossible to cut an accurate thread upon a lathebecause to do so all lost motion must be eliminated.

. It is the object of this invention to approximate such a condition byproviding a tool-holder which shall release itself from any tendency ofthe lathe to draw the cutting-tool into the work, and which will alsoprevent side-wise deflection of the cutter. It is necessary to avoid theside-wise deflection of the cutter to prevent changing the lead of thethread. In short, the object of the invention is to prevent anydeviation of the cutter and thereby maintain equi-distance betweensucceeding turns of the thread as measured along the axis of the screw.

To this end my invention comprises the parts and combinations recited inthe ap pended claims.

In the drawings, Figurel is a view in side elevation; Fig. 2 is a topplan view; Fig. 3 is a top plan view of the cutter-head; Fig. 4. is aview of the head partly in section and partly in elevation; Fig. 5 is adetail view in horizontal section, showing the application of the cutterto the head; Fig. 6 is a sectional view through the widest part of Fig.1; Figs. 7 and 8 are detail views of the cutter; Fig. 9 is a perspectiveview of the clamp which secures the cutter to the head.

Broadly speaking the tool is divided into two parts; first, the partincluding a shank and head by which the tool is secured in the lathe,and second, the head which immediately carries the operating tool properand is itself carried by the first part.

In this specification I have found it convenient to refer to the firstpart as a toolholder and to the second part as to a cutterhead, thoughit is obvious that in'certain Specification of Letters Patent.

Patented Mar. 2, 1920.

Serial No. 224,660.

lathetool post. The head of the tool-holder is recessed so that ineffect it is provided with parallel, separated arms 11 at one end whichextend from ahead 19. carried at one end of the shank 10.

A cutter head 13 has its shank lying within the recess of thetool-holder head or, as it may be stated, between the arms 11 of thetool-holder head. The cutter head fits into the toolholder head so thatit may be prevented from having any lateral movement, an object furthersecured by a screw 14 which passes through the parts or arms 11 andthrough a slot 15 formed in one side of the cutter head, thus permittingthe adjust ment of the cutter head within the arms or jaws of thetool-holder while securing it firmly against sidewise movement ordisplacement.

From the shank ofthe cutter-head extends at a right angle a projectionwhich is, in

effect, a flat spring-arm, the shank and the projecting spring-armforming a connection;

between the cutter head and the tool-holder head substantially of aninverted L-shape. This projection 16 is preferably formed as illustratedin section in Fig. 6 and fits a mortise or slot 17 in the head 12 of thetoolholder being secured in the desired position bymeans of a set-screw18. The purpose is to have the tool-head or cutter-head fulcrum upon thespring-arm 16 lying in its adjusted position in the slot 17 of the head12 of the tool-holder.

It will be observed that the spring-arm connection has, relatively, alimited horizontal adjustment in the tool-holder head, and that thespring tension efi'ect applies at the junction between the projectingspring-arm 16 and the shank of the cutter head.

It will be observed that the tool-holder head projects above thecutter-head and that the spring-arm passes into the top of thetool-holder head from the top of the vertical shank of the cutter-head.

It is necessary, to regulate the extent of movement of the cutter head,however, and to this end I have provided an adjusting screw orstop-screw 19 which takes into a threaded prdjection 190 at thebottom ofthe cutter-head, or, as it may be stated, at the opposite side from thespring-arm 16. The head of this stop-screw l9 lies opposite the face ofthe head 12 of the tool-holder and in the space between the parallelarms 11. Thatis to say, when the projecting arm or shoulder and theprojecting spring-arm 16 of the cutter-head are slid into place betweenthe arms 11 of the tool-holder head 12 there will be a space between thecutter-head shoulder and the head 12 of the tool-holder. At the bottomof this space lies the stopscrew 19, and its position within thethreaded projection 190 governs the distance of yield of the cutter-headand the amount of play of the cutter-head upon the fulcrum point of thespring-arm 16.

By this device I secure a firm working attachment between thecutter-head and the tool-holder, while at the same time permittlngthrough the action of the spring-arm 16, the tool-holder to releaseitself from any tendency of the lathe to draw the cutter into the work,and also preventing sidewise defiection of the cutter.

The cutter-head 13 is provided with a remeaaee Having fully described myinvention what I claim is,

1. A thread-cutting or similar instrument, comprising a tool-holder anda cutter-head, the tool-holder having a shank adapted to be fitted to alathe tool-post, the cutter-head having a spring-arm' capable ofhorizontal adjustment in the tool-holder.

' 2. A thread cutting or similar instrument, comprising a tool-holderand a cutter-head, the tool-holder having a shank adapted to be fittedto a lathe tool-post and the cutter head having a spring-arm with ahorizontal part adapted to enter the tool-holder and to be adjustedhorizontally substantially throughout its length in the tool-holder.

3. In" a thread-cutting tool or a similar instrument, the combinationwith a tool holder having a slotted head, of a cutterhead having a rightangle spring arm, the horizontal part of the spring arm adapted to beadjustably secured in the slot in the tool-holder head.-

45. In a thread-cutting or similar instrument, the combination of atool-holder and a cutter-head, the cutter-head having a spring-armhaving a vertical part extending above the cutter-head, the verticalpart having a projecting arm lying above the plane of the cutter-headand adjustably se cured in the tool-holder so that the spring effect isat the junction of the vertical part and the projecting arm.

5. In a thread-cutting or similar instrument, the combination of atool-holder having a recessed head, a cutter-head having a shank adjustably secured in the recess of the tool-holder head, and an armprojecting from the shank of the cutter-head into the recess of thetool-holder, horizontally adjustable therein and forming a springconnection between the tool-holder and the shank of the cutter-head.

In testimony whereof I aflix my signature.

i EDWIN P. DAVIS.

